Power tool torque release clutch operative in one direction



March 23, 1965 E. G. SPYRIDAKIS ETAL J 5 POWER TOOL TORQUE RELEASE CLUTCH OPERATIVE IN ow: DIRECTION Filed Aug. 9, 1962 4 Sheets-Sheet 1 INVENTORS EMANUEL 6. SPYR/DAMS JOHN M. GLAPP BY g EM w .TW

ATTORNEY March 23, 1965 E. G. SPYRIDAKIS ETAL 3,174,599

POWER TOOL TORQUE RELEASE CLUTCH OPERATIVE IN ONE DIRECTION Filed Aug. 9, 1962 4 Sheets-Sheet 2 FIG 5 INVENTOR'S EMANUEL 6'. SPYR/DAK/S JOHN M. GLAPP BY QM WTW ATTORNEY March 23, 1965 E. G. SPYRIDAKIS ETAL.

POWER TOOL TORQUE RELEASE CLUTCH OPERATIVE IN ONE DIRECTION Filed Aug. 9, 1962 4 Sheets-Sheet 3 iNVENTORS EMANUEL 6. SPYR/DAK/S JOHN M GLAPP ATTQRNEY March 1965 E. G. SPYRIDAKIS ETAL 3,174,599

POWER TOOL. TORQUE RELEASE CLUTCH OPERATIVE IN ONE DIRECTION 4 Sheets-Sheet 4 Filed Aug. 9, 1962 INVENTORS EMANUEL 6. SPYR/DAK/S JOHN M CLAPP ATTORNEY United States Patent Ofifice ,i'ii,599 Patented Mar. 23, 1%65 3,174,599 POWER T001, TORQUE RELEASE CLUTCH GPERATIVE IN GNE DERECTKON Emanuel G. pyridaltis and John M. Clapp, Athens, Pa, assignors to lngersoll-Rand Company, New York, N.Y., a corporation of New Jersey Filed Aug. 9, 1962, Ser. No. 215,883 7 Claims. (Cl. 192-66) This invention relates to a torque release clutch mechanism which opens a drive connection between a driving member and a driven member when the torque load on said members exceeds a predetermined value or magnitude. The torque release clutch mechanism of this invention is particularly useful for use in tools which apply torque loads to workpieces, such as power-operated wrenches or screw drivers.

In driving a screw or other threaded fastener home, into a holding position, it is highly desirable to use a power-operated tool containing a torque release clutch which automatically releases the torque driving force on the fastener after it is tightened to a given or predetermined torque load. It is also desirable to use the sarne tool to loosen or remove fasteners, but during this latter operation, it is desirable that the tool apply its maximum torque to the fastener. Hence, the release of the torque release clutch during the fastener removal operation is undesirable, since it limits the torque which can be applied to the fastener.

The principal object of this invention is to provide a torque release clutch mechanism for a torque tool which releases itself under a predetermined torque load when tightening a fastener and which locks itself against release when loosening or removing a fastener.

Another important object of this invention is to provide an improved torque release clutch mechanism which applies a predetermined tor no load to a workpiece and then releases to prevent the application of further torque to the workpiece.

A still further object of this invention is to provide a torque release clutch mechanism which releases itself under a predetermined torque load in one direction of rotation and locks itself against release in the other direction of rotation.

The invention is shown in the accompanying drawings wherein:

FIG. 1 is a fragmentary longitudinal section of the front portion of a power-operated torque tool with some parts being shown in elevation;

Fl G. 2 is a section taken on line 22 of FIG. 1;

FIG. 3 is a section taken on line 3-3 of FIG. 1;

FIG. 4 is a longitudinal section similar to FIG. 1 and showing the tool with its manuallyoperated push-clutch engaged;

FIG. 5 is a longitudinal section similar to FIG. 4 and showing the torque release clutch mechanism as it initially disengages;

FIG. 6 is a section taken on line 6-6 of FIG. 5;

FIG. 7 is a longitudinal section similar to FIG. 4 and showing the torque release clutch in a fully disengaged position;

FIG. 8 is a longitudinal section similar to FIG. 4 and showing the torque release clutch mechanism locked against release;

FIG. 9 is a section taken on line 99 of FIG. 8;

FIG. 10 is a fragmentary perspective view of the means for locking the torque release clutch mechanism against release; and

FIG. ll is an exploded perspective view of portions of the torque release clutch mechanism.

The power-operated screw driver 1 shown in the drawings includes a hollow cylindrical casing 2 formed by a rear portion 3 and a front portion 4 threadedly connected to the rear portion 3. The rear casing portion 3 houses a conventional rotary motor (not shown), such as an electric motor or a pneumatic motor driving an output shaft 5 through a set of reduction gears (not shown). The outptut shaft 5 is mounted at its front end on a bearing 6 carried by the front end of the rear casing portion 3. The front casing portion 4 includes a reduced diameter nose 7 on its front end. The nose 7 contains a conventional tool holder or spindle 8 which is rotatively mounted in and extends through an integral partition 9 located at the rear of the nose 7. The tool holding spindle S is surrounded by an O-ring 10 for sealing purposes and contains a polygonal socket 11 adapted to receive various types of tools or fastener engaging tips (not shown), such as a screw driver tip. All of the foregoing structure is conventional and usually found in power-operated screw drivers.

The torque-release clutch mechanism of this invention provides a drive connection between the output shaft 5 and the tool holding spindle 8. It includes a drive shaft id which extends axially through the front casing portion 4 and has a splined rear end 15 seated in a cooperating splined socket in the output shaft 5, thus providing a drive connection between the drive shaft 14 and the motor. The drive shaft 14 contains a hollow bore 16 which opens at its front end 17 and extends rearwardly therefrom along about two thirds of the length of the drive shaft 14. The rear end of the tool holding spindle 8 includes a reduced diameter stem 18 which projects rearwardly into the axial bore 16 of the drive shaft 14 for a short distance and is free to rotate therein, relative to the shaft 14.

The drive shaft 14 drives the tool holding spindle 8 through a series of three clutches designated in sequence, proceeding from the drive shaft 14 to the spindle 8, as follows: a lock-out clutch 19, a cam-thrust clutch 20 and a push-engaged clutch 21. These clutches are described hereafter in the above sequence.

Lock-out" clutch 19 A rear clutch sleeve 22 is keyed on the drive shaft 14 intermediate its ends by a plurality of key balls 23 seating in cooperating longitudinally-extending internal grooves 24 formed in the sleeve 22 and external grooves 25 formed in the drive shaft circumference, as shown in FIG. 2. The sleeve 22 is free to slide axially on the drive shaft 14 for a limited distance and is driven by the drive shaft through the key balls 23. As seen in FIG. 2, the external grooves 25 on the drive shaft 14 are wider than the internal grooves 24 on the sleeve 22 so that the sleeve 22 can rotate on the drive shaft through a small angle of limited relative rotation. The purpose of this limited relative rotation will be explained later.

An intermediate clutch plate 26 is slidably and rotatively mounted on the drive shaft 14 in front of the rear clutch sleeve 22 and connected to the rear clutch sleeve 22 through a series of inter-engaging notched or machicolated teeth or jaws 27 and 28 integrally formed on the plate 26 and sleeve 22, respectively. The interengaging jaws 27 and 28 form the lock-out" clutch 19. The sleeve 22 and plate 26 can slide axially on the drive shaft 14 between positions wherein the lock-ou clutch teeth 27 and 28 are engaged and positions wherein they are disengaged. When the teeth 27 and 23 are engaged, the sleeve 22 drives the clutch plate 26 and when disengaged, the clutch plate 26 is free to rotate relative to the sleeve 22.

The rear clutch sleeve 22 is biased forwardly by a light torsion spring 30 extending between the rear of the sleeve 22 and a washer 31 keyed to the drive shaft 14 and abutting a snap ring '32 engaging a circumferential groove in the drive shaft 14. The keying of the Washer '31 is performed by an inwardly extending tang 33 on the washer 31 fitting in a longitudinal kerf '34 cut in the drive shaft 14. The ends of the torsion spring 30 fit into longitudinal holes formed in the rear edge of the clutch sleeve 22 and the Washer 31, respectively, and the spring 30 is arranged to bias the clutch sleeve 22 in both a forward direction and-in a clockwise rotary direction, looking at the sleeve from its rear end. The purpose of biasing the clutch sleeve 22in a rotary direction will be seen later.

Cam-thrust clutch 20 A front clutch plate 36 is rotatively mounted on the front end-17 of the drive shaft 14 in front of the inter mediate clutch plate 26. The front clutch plate 36 rotates on ball bearings 37 engaging an erlarged shoulder 38 on the front end of the drive shaft 14.

Theintermediate and front clutch plates 26 and 36 are interconnected together by a series of circumferentially spaced balls 39 which seat in cooperating individual concave seats40 formed in the adjacent surfaces of both clutch-plates 126 and 36. The balls Sit and seats 40 provide a driving connection between the two clutch plates 26 and 36 so long as the plates are pressed together and the balls 39'remain in their seats. The balls 39 are angularly spaced about the drive shaft 14 by a perforated retainer disc 41 located between the clutch plates 26 and 36. The balls 39 and seats 44 form the cam-thrust clutch 20.

The intermediate clutch plate 26 is biased against the front clutch plate 36 by a heavy compression spring 46 which is engaged at its rear end by an adjustment mechanism for varying the compression load on the spring 46. The compression force exerted by the heavy spring 46 tends to keep the balls 39 in their seats 40 during the trans mission of artorque load through the cam-thrust clutch 20.. When the torque on the clutch plates 26 and 36 reaches a predetermined magnitude, determined by the load on the spring 46, the balls 3% roll out of their seats 40 and cam-thrust the intermediate clutch plate 26 rearwardly, against the spring 46, thus releasing the camthrust clutch 20. The magnitude of torque at which the balls 39 roll out of their seats 40 is changed by varying the compression load on the spring 46. The torque value at which the. cam-thrust clutch 2t? willrelease rises as the load on the. spring 46 increases and drops as the spring loaddecreases. As the.cam-thrust clutch 20 releases, it also cams the rear clutch sleeve 22. rearwardly on the drive shaft 14 to a retracted position.

The adjustment mechanism for the spring 46 includes a .nut 47 threaded onthe rear endof the drive shaft 14-, a collar 48 keyed on the drive shaft by means of an integral tongue 4? sliding on the kerf 34, and a spring seat ringSt) rotatably mounted on the collar 48 by ball bearing 51. Turning the nut 47 on the drive shaft 14 moves the collar, 48.and ring 51 forwardly or rearwardly to increase or decrease the tension on the spring 46. The nut 47 is latched in an adjusted position by detent balls 52 mounted in the rearface of the collar 48 and engaging detent cavities 53 in the front face of the nut 47.

The turning of the nut 47 on the drive shaft 14 is easily performed by means of a geared key 55, shown in FIG. 5,

which engages the gear teeth 56formed on the nut 47. The gear key 55 has an axial pin '57 at its geared end which seats inradial holes 58 formed in the collar 48 and is placed in its operative position by insertingit through an access hole 59 in the casing 2. It will be understood that the key 55 is only used during the adjustment of the load on the spring 46.

Push-engaged clutch 21 The front clutch plate 36 is provided on its front end with a pair of notches 61 adapted to receive a diametrically extending bar 62 carried on the rear face of a circular flange 63 integrally formed on the tool holding spindle 8. The notches 61 engage the bar 62 to connect thev front clutch plate 36 to the spindle 8 for driving purposes. This driving connection is accomplished by the tool spindle 8 moving axially rearward in the casing 2, caused by the operator pushing the screw driver 1 axially against its workpiece prior to the start of its operation. The pushengaged clutch 21 is formed by the notches 61 and the diametrical bar 62 The tool holding spindle 8' is biased forwardly awayfrom the main drive shaft 14 to keep the push-engaged clutch 21 normally disengaged, as shown in FIG. 1. This biasing force is provided by a compression spring 65, located in the axial bore 16 0f the drive shaft 14 and abutting the rear end of the bore 16 and a rod 66 which extends forward into contact with the rear stem '18 of the tool holding spindle 8. The rod 66 is freely slidable in the-bore 16 and, in effect, serves'as-an extension of the stem 18 of the tool holding spindle 8. In using the screw driver 1, an operator pushes the tool bit (not shown) ax ally forward against a workpiece, such as a fastener, with sufiicient force to overcome the spring 65 and to force the tool holding spindle Saxially rearward until the diametrical bar 62 on the spindle '8 is engaged in the notches 61 on the front clutch plate 36, as shown in FIG. 4-. This step places the screw driver in condition for operation. At the end of a fastener turning operation, the operator relaxes the forward axial thrust on the screw driver 1 and the tool holding spindle 8 moves forwardly to disengage the push-engaged clutch elements 61 and 62.

Zdeans for holding lock-out clutch open When the-torque load transmitted by the cam-thrust clutch 20 reaches a predetermined value or magnitude, the balls-39 roll out of'their seats 4! and force both the intermediate clutch plate 26 and the rear clutch sleeve 22 to move rearwardly on the drive shaft 14 to the rearward position shown in PIG. 5. After this operation occurs, the rear clutch sleeve 22is locked in. a rearward position and the intermediate clutch plate 26 again moves forwardly as the balls 39 drop into other ball seats 46, thus causing the engaged teeth 27 and 28 on the rear clutch sleeve 22 and intermediate clutch plate 26 to separate from each other and open or break the drive connection of. the-l ock-out clutch-19, as shown in FIG. 7.

The means forlocking the rear clutch sleeve 22 in its rearwardly retracted position shown in FIG. 5 includes a group of lock balls 68 carried in radial holes in the drive shaft 14 and biased outwardly into an annular groove 69 formedin the interior of the rear clutch sleeve :22. The lock balls 68 are biased radially outward by a conical cam 7 0 sliding on the rod 66 in thebore 16 of the drive shaft 14 and a compression cam spring 71 carried on the rod 66 and biasing the conical cam rearwardly against the lock balls 68.

The conical cam 70 is actuated to bias the lock balls 68 outwardly by the. rearward movement of the rod 66 in the drive shaftbore 16 when the push-engaged clutch 21 is engaged. When the push-engaged clutch 21 is disengaged, the conicalrcam 70 is moved forward by a shoulder 72. .on the rod 66 to release its outward biasing force on the lock balls 68.

'Mans for holding cam-thrust clutch closed outwardly into a.cooperating set of ball pockets '74, shown in FIG. 3. The pockets 74 are formed on the interior of the rear clutch sleeve 22 rearwardly of the annular groove 69' and are located where they are normally angularly displaced from the lock balls 68. When the drive shaft 14 is driven in a reverse direction, counter-clockwise looking at the rear end of the drive shaft 14, the torsion spring 3!) is overcome and the rear clutch sleeve 22 rotates relative to the drive shaft 14- through a limited angle until the sockets 74 are radially aligned with the lock balls 68, at which time the balls 68 move outward into the cavities 74 as shown in FIG. 8. The limited relative rotary movement of the sleeve 22 on the drive shaft 14 is allowed by the wide external grooves 25 on the drive shaft circumference holding the key balls 23, as shown in FIG. 2. When the lock balls 68 are seated in the pockets 74, as shown in FIGS. 8 and 9, the rear clutch sleeve 22 cannot move rearward on the drive shaft 14- and, as a result, the screw driver 1 can apply its full torque to the job of loosening or unscrewing a fastener.

Operation Prior to the start of operation, the screw driver 1 is in the condition shown in FIG. 1. Both of the lock-out and cam-thrust clutches 19 and 29 are closed and the push-engaged clutch 21 is open. The conical cam 70 is withdrawn from the lock balls 68 so that the lock balls 68 are not biased radially outward and the torsion spring 36 is biasing the rear clutch sleeve 22 in a rotary direction around the drive shaft 14 to the position shown in FIG. 3 wherein the ball pockets 74 are angularly displaced from the lock balls 68.

Before using the screw driver 1, the gear key 55 is used to turn the nut 4-7 until the heavy spring 45 is loaded to the desired magnitude, which determines the predetermined magnitude of torque under which the cam-thrust clutch 26 will open.

Initially, to tighten a fastener, the tool tip (not shown) is placed against the head of the fastener and the screw driver 1 is pressed axially forward to force the tool holding spindle 8 axially rearward in the casing 2 and to engage the push-engaged clutch 2.1. Simultaneously, the motor (not shown) is energized to start rotating the output shaft and drive shaft 14 in a clockwise direction.

As the push-engaged clutch 21 is initially engaged, the rod 66 is moved rearwardly in the bore 16 of the drive shaft 14, causing the conical cam 70 and its spring 71 to engage and bias the lock balls 68 radially outwardly, as shown in FIG. 4. However, since the rear clutch sleeve 22 is in its forward position at this time and the sockets 74 are angularly displaced from the lock balls 63, the balls 68 cannot engage either the annular groove 69 in the interior of the sleeve 22 or the pockets '74. Hence, at this time, the lock balls 68 are not performing any function,

but are merely coclcec and ready to lock the sleeve 22 when it moves into a locking position.

As the drive shaft 14 rotates, its drive torque is transmitted through the look-out clutch 19, the cam-thrust clutch 20 and the push-engaged clutch 21 to the tool holding spindle 8, thus driving the fastener inwardly into its hole. During this step, the parts of the clutch mechanism of the screw driver 1 are arranged as shown in FIG. 4.

As the fastener is driven into place by the screw driver 1 and seated, the torque load on the cam-thrust clutch 20 rises rapidly until it reaches a magnitude sutficient to cause the clutch balls 39 to roll out of their seats 40 and, as a result, to cam-thrust the intermediate clutch plate 26 and the rear clutch sleeve 22 rearwardly on the drive shaft 14.

The magnitude of torque on the cam-thrust clutch 20 corresponds to the torque load on the fastener being tightened; hence, the fastener is fully tightened when the camthrust clutch 20 opens. When the rear clutch sleeve 22 arrives at its fully retracted position, shown in FIG. 5, the lock balls 68, previously placed under an outward biasing force, move outwardly into the annular groove 69, to lock the clutch sleeve 22 in its retracted position.

Thereafter, the cam-thrust balls 39 move into other seats 46 and allow the intermediate clutch plate 26, under the biasing force of the spring 46, to return to its forward seated position, thereby opening the look-out clutch 19, as shown in FIG. 7. In this condition, the drive train between the drive shaft 14 and the tool holding spindle 8 is broken and the drive shaft 14 is free to rotate without a torque load, which causes the motor to increase its speed rapidly.

The release of the torque load on the tool motor signals the operator that the fastener is tightened properly and he removes the screw driver 1 from the fastener, thus allowing the tool holding spindle 8 to move axially forward and open the push-engaged clutch 21. The forward movement of the spindle 8 is accompanied by a corresponding forward movement of the rod 66, which forces the conical cam 7t} away from the lock balls 68. Thereafter, the lock balls 68 move radially inward and the lock-out clutch 19 closes, resulting in the screw driver 1 returning to the condition shown in FIG. 1.

During the operation of the screw driver 1 in a reverse direction to loosen or unscrew a fastener, the cam-thrust clutch 24) is prevented from opening regardless of the torque placed on it. This operation is as follows.

The screw driver tip is engaged against the fastener and pushed axially forward to engage the push-engaged clutch 21 and to bias the lock balls (58 radially outward in the same manner as earlier described in the fastener tightening operation. Simultaneously, the motor is energized to drive the drive shaft 14 in a counter-clockwise or reverse direction.

Placing a counter-clockwise torque on the drive shaft 3.4 acts against the torsion spring 30 and turns the drive shaft 14 counter-clockwise, looking at FIG. 3, relative to the rear clutch sleeve 22 to a position wherein the lock balls 68 are radially aligned with the pockets 74. Simultaneously, the lock balls 68, previously placed under an outward biasing force, are moved radially outward by the conical cam 70 into the pockets 74, to the positions shown in FIGS. 8 and 9, so as to prevent the rear clutch sleeve 22 from moving rearward on the drive shaft 14. The movement of the lock balls 68 into the pockets 74 hold the can1-thrust clutch 20 against opening under a torque load. Thereafter, the full counter-clockwise torque of the motor can be applied to the fastener without the clutches l9 and 20 releasing to stop the transmission of torque to the fastener.

When the fastener is withdrawn from its hole, the operator stops the screw driver motor and removes the screw driver from the fastener to again allow the pushengaged clutch 21 to open and remove the outward bias ing force from the lock balls 68. Thereafter, the lock balls as move inward out of the pockets 74 and the torsion spring 30 returns the clutch sleeve 22 to the position shown in FIGS. 1 to 3, wherein the screw driver is ready for another operation.

It will be understood that although only one embodiment of the invention is specifically described, the invention may embrace various other embodiments which are obvious from an understanding of the described embodiment and are embraced within the claims of the invention.

Having described our invention, we claim:

1. A torque load transmission mechanism comprising: a driving member; a driven member; a clutch mechanism d-rivingly interconnecting said members and adapted to be repeatedly opened and closed, said clutch mechanism being operative in one direction of rotation of said driving member to open and release said driven member from said driving member at a predetermined torque load; said clutch mechanism including an element which moves axially on one of said members during release of said clutch mechanism; latch means operative to prevent said clutch mechanism from opening and releasing said members when said driving member is driven in the other rotary direction; and said latch means being operative to prevent the axial movement of said element savanna during the rotation of said driving member in the other tive to move radially'into a cooperating detent seat forlatching said element'against axial movement; and a torsion spring operative to normally maintain said detent seat in an angularly displaced location relative to said detent means, said torsion spring being overcome by driving said driving member in the other rotary direction whereby said detent means is rotated to a radially aligned position with said detent seat and seated in said detent seat to. latch said element against axial movement.

3; A torque-transmitting apparatus comprising: a hollow drive shaft; first and second clutch sleeves mounted on said shaft for axially slidable movement and having normally interengaged clutch teeth locking the two clutch sleeves against relative rotation; said first clutch sleeve being mountedon said drive shaft by a driving connection to be driven thereby; a third clutch sleeve rotatably mounted on said shaft; torque clutch release means drivingly interengaging said third clutch sleeve with said second clutch sleeve; said torque clutch release means being operative to force said' first and second clutch sleeves axially away from saidthird clutch sleeve when the torque on said torque clutch release means exceeds a predetermined load; a driven member connected to said third clutch sleeve to be driven thereby; first biasing means yieldably forcing saidsecond clutch sleeve'axially against said third clutch sleeve; second biasing means yieldably forcing said first clutch sleeve axially against said second clutch sleeve; and detent means operative to lock said first clutch sleeve in an axially retracted and spacedposition'from said second clutch sleeve after being moved to said retracted position by said torque clutch release means.

4. The torque transmitting apparatus of claim 3 including latch means operative in one direction of rotation of said drive shaft to latch and prevent said first clutch sleeve from moving'to said retracted position so that saidclutch sleeves cannot disengage from each other.

5. Thetorque transmitting apparatus of claim 4 wherein said latch means includes: detent means mounted in said drive shaft for outward radial movement; a detent seat formed in said first clutch sleeve and adapted to receive said detent means when said latch means prevents said clutch sleeves from being disengaged; said first clutch sleeve being mounted on said drive shaft for relative rotation through less than 360; and a tor sion spring mounted on said shaft and operative to normally hold said first clutch sleeve in a relative position on said shaft wherein said detent seat is angularly.

displaced from said detent means, said spring being overcome or wound by driving said shaft in said one direction whereby said first clutch sleeve is rotated on said shaft to a position wherein said. detent means is radially aligned with said detent seat.

6.- The torque transmitting apparatus of claim 5 including: cam means movable axially in said hollow drive shaft and operative to force said detent means radially outward into said detent seats;

a 7. A torque applying toolcomprising: a casing; a

rotary motor in said casing; a drive shaft rotatably.

mounted in said casing and connected to said rotary motor to be driven thereby; a workpiece engaging member rotatably mounted on said casing; a torque release clutch interconnecting said drive shaft and said member and including a clutch element adapted to slide axially on said drive shaft to an axially retracted clutch-disengagedposition when the torque on said drive shaft in one rotary direction exceeds a predetermined value; detent means mounted in said drive shaft'to move radiallyoutward; a'detent seat provided in said clutch element and adapted'to receive said detent meansto prevent said clutch element from moving axially on said drive shaft to its retracted clutch-disengaged position; a torsion spring on said drive shaft normally rotating said clutch element on said drive shaft to a relative position wherein said detent means is not radially aligned withsaid detent seat, said torsion springbeingarranged to be overcome by a torque load on said drive shaft in the other rotary direction to rotate'said clutch element on said drive shaft to a position wherein said detent means is radially aligned with said detent seat; and means in said drive shaft and operative, in response to theengagement of said workpiece engaging member with a workpiece, to biassaid detent means radially outward from said drive shaft.

References Cited by the Examiner UNITED STATES PATENTS 1,537,629 5/25 Street 19256 1,593,732 7/26 Street 10-135 XR 2,259,839 10/41 Van Sittert 192-56 XR 2,765,890 10/56. Pedersen et al. 192 56 2,942,481 6/60 Gilbert 192-56 XR 3,020,789 2/62 Etzkorn 192-56 XR FOREIGN PATENTS 813,687 5/59 Great Britain.

DAVID J. WILLIAMOV/SKY, Primary Examiner.

BROUGHTON G. DURHAM, Examiner. 

1. A TORQUE LOAD TRANSMISSION MECHANISM COMPRISING: A DRIVING MEMBER; A DRIVEN MEMBER; A CLUTCH MECHANISM DRIVINGLY INTERCONNECTING SAID MEMBERS AND ADAPTED TO BE REPEATEDLY OPENED AND CLOSED, SAID CLUTCH MECHANISM BEING OPERATIVE IN ONE DIRECTION OF ROTATION OF SAID DRIVING MEMBER TO OPEN AND RELEASE SAID DRIVEN MEMBER FROM SAID DRIVING MEMBER AT A PREDETERMINED TORQUE LOAD; SAID CLUTCH MECHANISM INCLUDING AN ELEMENT WHICH MOVES AXAILLY ON ONE OF SAID MEMBERS DURING RELEASE OF SAID CLUTCH MECHANISM; LATCH MEANS OPERATIVE TO PREVENT SAID CLUTCH MECHANISM FROM OPENING AND RELEASING SAID MEMBERS WHEN SAID DRIVING MEMBER IS DRIVEN IN THE OTHER ROTARY DIRECTION; AND SAID LATCH MEANS BEING OPERATIVE TO PREVENT THE AXIAL MOVEMENT OF SAID ELEMENT DURING THE ROTATION OF SAID DRIVING MEMBER IN THE OTHER ROTARY DIRECTION. 